// Trafic control with Distance sensor using Arduino Uno

#include <Tiny4kOLED.h>

// Define the pin for the LEDs
const int greenLedPin = 8;
const int orangeLedPin = 10;
const int redLedPin = 12;

// Define the pins for the ultrasonic sensor
const int echoPin = 4;
const int trig_Pin = 6;

float cm;
float inches;

void setup() {
  Serial.begin(9600);

  // Set LED pins as outputs
  pinMode(greenLedPin, OUTPUT);
  pinMode(orangeLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);

  // Set ultrasonic sensor pins
  pinMode(trig_Pin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Initialize the OLED display
  oled.begin();
  
  // Clear the display
  oled.clear();
  
  // Turn on the display
  oled.on();
  
  // Set the font
  oled.setFont(FONT6X8);
}

long readUltrasonicDistance(int trig, int echo) {
  // Clear the trigger
  digitalWrite(trig, LOW);
  delayMicroseconds(2);

  // Sets the trigger pin to HIGH state for 10 microseconds
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  
  // Reads the echo pin, and returns the sound wave travel time in microseconds
  return pulseIn(echo, HIGH);
}

void loop() {
  // Measure the distance in cm
  cm = 0.0344 / 2 * readUltrasonicDistance(trig_Pin, echoPin);

  // Convert cm to inches
  inches = cm / 2.54;
  
  // Clear the OLED display
  oled.clear();
  
  // Display the distance
  oled.setCursor(0, 0);
  oled.print("---Distance---");

  oled.setCursor(0, 2);
  oled.print(F("Inches: "));
  oled.print(inches, 1);

  oled.setCursor(0, 4);
  oled.print("CM: ");
  oled.print(cm, 1);

  // Check if the distance is below 100 cm
  if (cm < 100) {
    oled.setCursor(0, 6);
    oled.print("!!! Car near by !!!");

    // Light orange and green signal to GO!
    digitalWrite(orangeLedPin, HIGH);
    delay(2000);
    digitalWrite(orangeLedPin, LOW);
    delay(1000);
    digitalWrite(greenLedPin, HIGH);

    Serial.print("Measured distance in cms: ");
    Serial.println(cm);

    delay(10000);
    digitalWrite(greenLedPin, LOW);
  } else {
    oled.setCursor(0, 6);
    oled.print("--Car far away--");

    // Light orange and red signal to STOP!
    digitalWrite(orangeLedPin, HIGH);
    delay(2000);
    digitalWrite(orangeLedPin, LOW);
    delay(1000);
    digitalWrite(redLedPin, HIGH);

    Serial.print("Measured distance in cms: ");
    Serial.println(cm);

    // Pause for 10 seconds
    delay(10000);
    digitalWrite(redLedPin, LOW);
  }

  // Clear the OLED display
  oled.clear();
}